+++
title = "Beginner's guide to Git" 
date = 2024-07-19
+++

## WhatIs Git?

Git is a version control system. It is a program that allows you to roll back changes to files before they were previously saved.  
It also helps multiple people work on a project. Thus it can combine changes made by several developers.

There are services that provide access to git repositories, the most popular is [GitHub](https://github.com/).

## How to download someone's repository?

1. Clone it with `git clone REPO_LINK`  
```bash
git clone https://github.com/oneshotws/hackerProg
```
First time - we will get prompt, answer `yes` (details below).


## Getting started - How to make repo?

0. __Register__ on Github 

1. Create a Git __repository__
![](./images/10.png)
![](./images/11.png)
2. Choose a __license__
	- __"MIT License"__ if you don't know what to choose
	![MIT](./images/21.png)
	- __"GNU GPLv3"__ if you want your project to be free software.
	![GNU GPLv3](./images/22.png)
	
3. __Clone__ (download) the repository `git clone REPO_LINK`.  

	Get repo link (click on "Code"): ![](./images/31.png)
	If we clone via SSH link, we will get promt:
```bash
~ ➤ git clone git@github.com:oneshotws/hackerProg.git
Cloning into 'hackerProg'...
The authenticity of host 'github.com (140.82.121.4)' can't be established.
ED25519 key fingerprint is SHA256:+DiY3wvvV6TuJJhbpZisF/zLDA0zPMSvHdkr4UvCOqU.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])?
```

- write `yes`, press enter. This should happen only once.  
And we will get an error:
	
```bash
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'github.com' (ED25519) to the list of known hosts.
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

```  

Previously GitHub said we have not added the SSH key to our account.   
	<!-- ![](./images/32.png) -->

	
 4. __Generate__ an SSH key (if you don't have one!) - `ssh-keygen` and press enter 3 times:
 ```bash
 ~ ➤ ssh-keygen
 Generating public/private ed25519 key pair.
 Enter file in which to save the key (/home/casual/.ssh/id_ed25519):
 Enter passphrase (empty for no passphrase):
 Enter same passphrase again:
 Your identification has been saved in /home/casual/.ssh/id_ed25519
 Your public key has been saved in /home/casual/.ssh/id_ed25519.pub
 The key fingerprint is:
 SHA256:ut0/9NgtyQEmOozmVOUBFbnfAgScz9IkwPCKalOCff0 casual@Casual-PC
 The key's randomart image is:
 +--[ED25519 256]--+
 |    .o.oo=oo     |
 |     .. + *      |
 |      .  X o     |
 |.. . o  o O o    |
 |..o.o .+So = o   |
 | .o.  +o+   + o  |
 |.o   +. E. . * + |
 |. .   .o .  o * .|
 |      . . .... . |
 +----[SHA256]-----+
 
 ```
  Output the public SSH key with `cat` and copy it. 
  ``` 
  ~ ➤ cat /home/casual/.ssh/id_ed25519.pub
  ssh-ed25519 AAAAC3NzaC1lZDI1HEX5AAAAIIMaB2mluyXjROHI8GJ2o9xfvj+uiol/GbPnwJDzZkFm casual@Casual-PC
  ``` 
<!-- ![](./images/34.png) -->
Next we click the "add a new public key" hyperlink and paste in our SSH public key.
![](./images/33.png)
![](./images/35.png)
(note - screenshot have different key)  
This should happen only once.  

 After that we will be able to download repositories via SSH and upload changes (`git push`), what will prevent problems in the future.  
 Run `git clone git@github.com:oneshotws/hackerProg.git`:
 
![](./images/36.png)
![](./images/37.png)
<!-- ```bash -->
<!-- ~ ➤ cd hackerProg -->
<!-- hackerProg ➤ ls                   -->
<!-- LICENSE  main.go  README.md -->
<!-- hackerProg ➤ bat main.go         -->
<!-- ───────┬────────────────────────────────────────────────────────────── -->
<!--        │ File: main.go -->
<!-- ───────┼────────────────────────────────────────────────────────────── -->
<!--    1   │ package main -->
<!-- ───────┴────────────────────────────────────────────────────────────── -->
<!-- ``` -->

  
	
5. __Develop__ your program.  
Once you make the changes you want, upload them to the repository using:  
`git add . && git commit -am 'new feature' && git push`.  

	However, you will probably find that git doesn't know who you are, so it will ask you to add your email and name with `git config`.  
	![](./images/41.png)
	- `git add .` - adds new files to the repository (not all files are tracked in folder that will be uploaded to remote repository)  
	- `git commit -am 'new feature description'` - saves (commits) changes to the repository that you can rollback to later.   
	- `git push` - uploads them to GitHub.
	
	After that, our local changes will be displayed on github.  


---

[Other typical Git problems.](https://ohshitgit.com/)

---

Btw, it's experemental post. Do you like this approach that we deal with problem as we are doing it first time together? Or do you prefer more easier to read - step by step (HowTo) guide?

{{< source >}}
My PHD2 presentation
{{< /source >}}